1. Field of the Invention
The present invention relates to a water purification system, and more particularly to a halogen generator.
2. Description of Related Art
Portable self-contained spas have become popular in recent years. Such spas are easy installed and powered by existing electrical lines or dedicated electrical hook-ups.
Once installed, the homeowner must sanitize the spa to prevent the proliferation of disease-causing micro-organisms, such as, for example, Pseudomonas aeruginosa. Typical spa maintenance requires adding granular sodium dichloro-isocyanurate as a sanitizing agent to control such bacteria growth. Bromine alternatively can be added as a sanitizing agent. Bromine preferably is used as the sanitizing agent in the spa because it remains in liquid form at 100.degree. F., unlike chlorine.
Many spa owners today, however, do not properly maintain their spas. Some owners do not adequately sanitize their spas despite the danger of unhealthful bacteria growth. Other owners over-sanitize their spas which can damage spa equipment, including the heater or the spa shell.
In the pool industry, some pool owners recently have used electrolytic cells with their pool or spa to produce chlorine or bromine automatically by electrolysis. Such electrolytic cells eliminate the need to constantly adjust the chlorine or bromine levels by adding chemicals to the pool. Examples of electrolytic cells used to generate sanitizing agents are disclosed in U.S. Pat. Nos. 4,992,156, 4,790,923, and 4,201,651.
Although such electrolytic cells simplify the proper maintenance of chemical levels in the pool, other problems arise in connection with their use. Many pool owners commonly neglect the filtration system of the pool, which, as a result, clogs and reduces the flow rate through the water circulation line. Because prior electrolytic cells commonly are connected in series with the main spa circulation line and depend on a minimum flow rate through the cell, the effectiveness of the cell decreases. In addition, an insufficient flow rate through the cell may present the potential for explosion as such cells commonly produce hydrogen and oxygen gases which become entrapped within the cell if not flushed into the pool by water flow through the cell.
Scaling or plating out of calcium carbonate and other salts on the cathode of the electrolytic cell during operation presents another formidable maintenance problem associated with electrolytic units used in hard water. In water having a hardness greater than 700 parts per million ("hard water"), scale deposits from the water and builds up on surfaces adjacent to a water flow. Electrolytic cells used in hard water commonly experience significant scale build-up which causes water flow problem. Scale typically builds up and clogs small openings and conduits in the equipment. Thus, some manufacturers recommend using their equipment in water having a total hardness less than 300 parts per million.
Other manufacturers of electrolytic cells have attempted to resolve the problems associated with scaling in a variety of ways; however, prior attempts offer less than an adequate solution. Prior electrolytic cells which reverse the polarity of the electrodes to remove scale tend to have shortened electrode life. Other electrolytic cells have relied on high flow water rates through the cell to remove scale, but flow through the cell may be affected by the inefficiency of an external pump or by a clogged filter. And some manufacturers recommend manually cleaning of the cell electrodes by soaking them in acid. Although effective, this process is dangerous, time-consuming, and may not be feasible, given the industry trend toward limiting consumer access to the spa equipment.